STUDIES OF REPRODUCTIVE ELEMENTS: I. 17 



during the firöt stages. At first the spermatic micleiis is relatively 

 small and generally oblong, and stains very deeply and uniformly 

 with colouring matters, but soon it shows within it a lighter space 

 in which chromatic fibres become more or less distinct (figs. 31- 

 33). At about the same time that the egg-nucleus begins to enlarge, 

 the spermatic nucleus also swells up gradually, and assumes a spherical 

 form, always remaininu' a little lari>-er than that of the euü'. The chro- 

 matic elements are yery distinctly to Ije seen, but they are so much 

 comoluted that it is \'ery difficult to determine their niunber (figs. 

 36-4U). 



The nuclei of the egg and of the spermatozoa gradually approach 

 each other till they come to lie close together (figs. 36-49), but the 

 nuclear memijranes continue distinctly ^ isible up to the stage of the 

 segmentati(jn of the egg. The clu'omatic elements of the nuclei 

 gradually pass, during these stages, from their so called resting stage 

 to a state of activity again, and the indi\idual fibres become more and 

 more distinct. Tlieir nundjer is howe\er, no I<_)ni>'er four but eia'ht. 

 AVhether tin's is l)rought aljout l)y the trans\ erse diyisi'jn of the ele- 

 ments or b\- a loiigitudinal di\isi(ni, 1 am not able to tell. Still 1 

 thiidv 1 am (piite justified in supposing that this doubling of the 

 number of chromatic elements before tlie formation of a, spindle is 

 the same phen«jmen(jn as that oljserved by Flemiiimg^'^ and others in the 

 division of many animal and vegetable cells, (Flcmmhu/s '' hetero- 

 typische Form "). 



The entire process of the copulation of the two nuclei ii}) to the 

 beuinninii' of the seu'menhilion will Ik; seen by lookiu"" al liü-s. 36-0'». 

 Fig. 36 re[)resents <jniy a. small part ol" an egir in which both 

 nuclei are to be seen lyinu' nl some ili-laiici' from one aiioliier. The 

 smaller ujtper one is I he egg- nucleus and the larger one helow is tiial (<t" 

 the spermatozoon ; both are more or less in the *• skein " stage. Fiu". 37 



